Oscillator ignition system



March 21, 1961 LE ROY E. DILGER ET AL 2,976,461

OSCILLATOR IGNITION SYSTEM Filed Feb. 6, 1959 2 Sheews-Sh'eet 1 INVENTORS LE Row E. D\ Lean Fl 6. 3 I B SYLVESTER AS-rmasn v www.mw

March 21, 1961 LE ROY E. DILGER ETAL 2,976,461

OSCILLATOR IGNITION SYSTEM Filed Feb. 6, 1959 2 Sheefs-Sheet 2 CLASS B Amrmnsn INVENTORS LeRov E. Duesa svLvcu-sn A. Srusaaa wwww ATTORNEY OSCILLATOR IGNITION SYSTEM Le Roy E. Dilger and Sylvester A. Stuiber, Milwaukee, Wis., assignors to Globe-Union Inc., Milwaukee, Wis., a corporation of Delaware Filed Feb. 6, 1959, Ser. No. 791,562

12 Claims. (Cl. 315-205) This invention relates to spark ignition systems and more particularly to transistor oscillator ignition systems.

In most present day passenger automobiles and other vehicles where spark ignition systems are used, breaker points having heavy current carrying duties get burned and must be frequently replaced. Also the single spark system permits carbon fouling of the plugs particularly at idling speeds.

An object of this invention, therefore, is to provide an ignition system which eliminates the problem of breaker point burn-out.

Another object is to provide such a system which reduces the likelihood ofspark plug fouling, provides easier starting and more efficient fuel consumption.

Still another object is to provide a low tension ignition system which is self-protective and permits the use of storage capacitors without intervening switches.

The first of these objects is obtained by employing a transistor square-wave oscillator which is stopped by short circuiting a so-called switching winding to momentarily heavily load the oscillator. This switching States atent winding is shorted by standard cam-operated breaker points. However, the current and voltage in the switching winding falls to zero almost instantaneously with the closing of the breaker points. This electrically relieves the breaker points so that burn-out ceases to be a problem and mechanical durability is the only wear factor that remains.

Spark plug fouling is practically eliminated by this same system because the oscillator having a high frequency delivers a shower or cascade of sparks at the plug electrodes during each firing cycle. This spark shower, or series of sparks, provides adequate ignition energy to eflect more nearly complete combustion at starting, idling and running resulting in fuel economy and easier starting.

In low tension ignition systems a lower unidirectional voltage and higher amperage energy spark is employed by first charging a storage capacitor from the power supply and then discharging it by connecting it to the plug. Heretofore this required switches to connect and disconnect the capacitor to and from the power supply and to and from the plug. By using. a transistor oscillator to generate the power supplied to the secondary winding of the circuit the use of such switches is eliminated and the capacitor is continually connected to the secondary and directly connected to the plug by the usual distributor. This is possible because during discharge of the storage capacitor to the plug the oscillator, in trying to maintain the charge on the capacitor, uses enough current to reduce the power available in the feed-back winding to the .point where the oscillator stops oscillating during the sparking period. Hence, it is not necessary to have a switch to disconnect the capacitor from the power supply. When the plug is disconnected by the distributor the oscillator returns to normal operation and the capacitor is recharged.

Other objects and advantages of the present invention 2,976,461 Patented Mar. 21, 1 96 1 2 will appear from the following description which:

Fig. 1 is a schematic view of avtransistor oscillator ignition system embodying the present invention and iland claims in lustrating a switching winding for controlling switching in time with engine speeds by standard cam-operated breaker points not carrying appreciable voltage and current when closed;

Fig. 2 is a schematic view of a system like that illustrated in Fig. l employing an amplifier which permits the system to be used for high speed multi-cylinder engines; and

Fig. 3 is a schematic view of a low tension ignition system using a transistor oscillator like that illustrated in Figs. 1 and 2 with the storage capacitors continuously connected to the power supply. p

The ignition systems shown in the drawings each employ a transistorized square wave oscillator in conjunction with a step-up transformer. In the high tension systems of Figs. 1 and 2 the voltage is stepped up to the customary level for such systems. In the low tension system of Fig. 3 the step-up is less, as is standard for such systems. Since the amounts of such voltages are well known to those skilled in this art and are not essential to this invention, no description will be given.

The primary circuits for the systems shown are subof the power supply is connected to the center tap of the oscillator winding 12 and through a suitable resistor 29 to the center tap of the feed-back winding 14. The ends of the oscillator winding are. connected to the collectors of such transistors.

In the high tension systems of Figs. 1 and 2 the switch- 2 ing of the oscillator in time with the engine speed is accomplished by a switching winding 22 in the primary side of the step-up transformer which is shorted momentarily by standard cam-operated breaker points 24 in conjun'ction with a standard ignition capacitor 26. The oscillai tor is heavily loaded and oscillation prevented whenever the breaker points 24 short the switching winding 22.

p This is timed in a well known manner so that during the otf position of the distributor the breaker. points are closed. Almost simultaneously withthe closing of the switching circuit the voltage in it drops to zero and no current flows.

longer restricts the operation of the oscillator which, during such sparking period, provides a series or cascade of sparks instead of the single spark of thecus'tomary high tension system.

In the high tension systems, of. Figs. 1 and 2 there are the customary spark plugs 28 which are connected in In the high tension system of Fig. 2 a. class TB.

amplifier is used to step up power output andy lg -g v for high speed multi-cylinder engines. This includes 3' Thus, the breaker points do not burn out and need replacement only because of mechanical wear; 1 When the distributor closes a circuit to a plug, the breaker points 24 are open and the switching winding 22 no secondary winding 36 designed for the proper voltage and current of a standard well known class B amplifier. Such amplifier uses two transistors 34 in push-pull relationship with ends of the secondary connected tothe bases of such transistors and the collectors ofsuch transistors connected to theends of a primary winding 38 of a final step-up transformer. A source of unidirectional biasing voltage 40 has its positive terminal connected through a resistor 42 to the center tap of the winding 36 and its negative terminal connected'to (l) the center tap of winding 38, (2) through a resistor 44 to the center tap of winding 36, and (3) to the final secondary circuit. There is a capacitor 46 connected between the collectors of the transistors. In this amplification circuit the transistors (or tubes) are biased to approximately cut-ofi. Thus, all the current conduction takes place in one transistor at a time giving a large current change and output of energy at the final step-up transformer without undue heat losses.

While the controlling of the oscillator in the high tension systems is preferably accomplished by the breaker point shorted switch winding 22 heretofore described, there are other means for switching such as shunting the feed-back winding 14, as indicated in the broken lines of Fig. 1, by camoperated breaker points 48 or shunting part of the collector-primary winding 12 as indicated in the broken lines of Fig. 2 by cam-operated breaker points 50.

In the low tension system shown in Fig. 3 the oscillator circuit is the same as heretofore described. However, the secondary circuit operates from a. step-up transformer having a secondary winding 52 which produces the much lower voltage customary with such systems. Also this system has creepage type plugs 54 connected for successive discharge by a standard distributor 56. The ends of the secondary winding 52 are connected to a full wave voltage doubler circuit. Said voltage doubler circuit has (1) a first rectifier 58 and a sparking capacitor 60 connected in series and (2) a second rectifier 62 and sparking capacitor 64 connected in series both connected in parallel with each other and in series with the secondary winding 52. The positive plate of capacitor 60 is connected to the rotor of the distributor 56 and the negative plate of capacitor 64 is connected to the ground side of the plugs 54.

Whenever the capacitors 60 and 64 are discharging across a spark plug 54 with the distributor closed a heavy current demand is made on the oscillator circuit to re-- charge the capacitors because of the continuous connection. However, this heavy demand reduces the amount of power available in the feed-back winding 14 to a level where the oscillation of the power supply is cut off so that the system is self-protecting during the sparking period. As soon as the distributor 56 disconnects a plug 54 the output returns to normal and the capacitors are recharged. This feature permits the sparking or storage capacitors to be constantly connected and thus does away with cam-operated switches lessening the expense of the system and making it more trouble-free.

We claim:

l. A transistor oscillator low tension ignition system having a step-up transformer with a secondary winding, said oscillator having a feed-back winding in inductive relation with said transformer, a storage-sparking capacitor and rectifier constantly connected to said secondary winding, and a distributor for intermittently connecting said capacitor to a spark plug, said oscillator ceasing to oscillate when said distributor connects to a spark plug.

2. An ignition system for a combustion engine comprising, a primary circuit, a secondary circuit in inductive relation to said primary circuit, a self-exciting transistor oscillator having a feed-back winding and an oscillator winding in said primary circuit, a unidirectional voltage power supply connected to said oscillator, a distributor and a spark plug in said secondary circuit and means including a rectifying and capacitive storage circuit in said secondary circuit whereby the oscillator is loaded to cut-off during the sparking intervals.

3. An ignition system for a combustion engine comprising, a primary circuit, a secondary circuit in inductive relation to said primary circuit, a self-exciting transistor oscillator. including a pair of transistors connected in push-pull relationship, each of said transistors having a feedback winding and an oscillator winding in said primary circuit, a unidirectional voltage power supply connected to said oscillator, a distributor and a spark plug in said secondary circuit and means operative to reduce the induced voltage in said feedback windings to cut off said transistors, said means being synchronized with said distributor and rendered effective solely by said voltage power supply.

4. An ignition system for a combustion engine comprising, a primary circuit, a secondary circuit in inductive relation to said primary circuit, a self-exciting transistor oscillator including a pair of transistors connected in push-pull relationship, each of said transistors having a feedback winding and an oscillator winding in said primary circuit, a unidirectional voltgae power supply connected to said oscillator, said oscillator having a high frequency to deliver a cascade of sparks during each sparking period, a distributor and a spark plug in said secondary circuit to determine each sparking period, and means operative to reduce the induced voltage in said feedback windings to cut olf said transistors, said means being synchronized with said distributor and rendered effective solely by said voltage power supply.

5. The ignition system according to claim 4 in which said means operative to reduce the induced voltage in said feedback windings comprises a switching winding in inductive relation to said primary circuit, and switching means operative to short circuit said winding thereby reducing the voltage in said feedback windings to cut off said transistors when said distributor is disconnected from a spark plug.

6. The ignition system according to claim 4 in which said means operative to reduce the induced voltage in said feedback windings comprises a shunt circuit in said oscillator Winding, and switching means operative to close said shunt circuit thereby reducing the voltage in said feedback windings to cut off said transistors when said distributor is disconnected from a spark plug.

7. The ignition system according to claim 4 in which said means operative to reduce the induced voltage in said feedback windings comprises a shunt circuit in said feedback winding, and switching means operative to close said shunt circuit thereby reducing the voltage in said feedback windings to cut off said transistors when said distributor is disconnected from -a spark plug.

8. A high tension ignition system according to claim 4 in which a class B amplifier is interposed between said primary circuit and said secondary circuit.

9. A high tension ignition system according to claim 5 in which said switching means is comprised of camoperated breaker points.

10. A high tension ignition system according to claim 9 in which the said breaker points and distributor are timed so that when the distributor is not delivering current to said spark plug the breaker points are closed whereby the oscillator is loaded to cut-off.

11. A low tension ignition system having a transistor oscillator and a step-up transformer, said oscillator having a feed-back winding in inductive relation to said transformer, a full-wave voltage doubler rectifying circuit continuously connected to the secondary winding of said transformer, and a distributor continuously connected to said circuit, said oscillator ceasing to oscillate when said distributor connects to a spark plug.

12. A low tension ignition system for a combustion engine comprising a transformer having a primary oscillater winding, a feed-back winding and a secondary winding, a power supply of suitable unidirectional voltage having its negative terminal connected to the center tap of said oscillator winding, a pair of transistors having their emitters connected to the positive terminal of said power supply and through a resistor to the center tap of said feed-back Winding, the bases of said transistors being connected to the ends of said feed-back winding, the collectors of said transistors being connected to the ends of said oscillator winding, the center taps of said primary oscillator and feed-back windings being connected through a resistor, and a full wave voltage doubler rectifying circuit continuously and operatively connected to said secondary winding to discharge through a distributor to a spark plug, said oscillator ceasing to oscil- 15 late during the interval said voltage doubler circuit is connected through a distributor to a spark plug.

References Cited in the file of this patent I UNITED STATES PATENTS Varley May 8, 1917 Snook June 22, 1926 Short et a1. Jan. 2, 1951 Brunelle et al July 1, 1952' Pearlman May 29, 1956 Uchrin et a1 Nov. 19, 1957 Driver July 15, 1958 Giacoletto Mar. 17, 1959 FOREIGN PATENTS Great Britain Jan. 23, 1957 

